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关键词： 标准皮托管   激光多普勒测风仪   量值溯源   不确定度  

摘要： 计量检定规程《皮托管》JJG 518-1998中,只对工作级皮托管的计量检定方法进行了阐述,而高等级的标准皮托管的量值溯源一直没有明确规定。为保证高等级的标准皮托管测量数据的准确、可靠,对其测量结果的不确定度分析很有必要。选择激光多普勒测风仪作为标准器建立适应科技发展的量值溯源体系,对标准皮托管进行计量检定,并给出新体系下标准皮托管校准系数测量结果的不确定度评定分析。该方法对标准皮托管测量结果的可信度评定以及计量检定规程《皮托管》JJG 518-1998的修订具有较强的参考价值。

关键词： Flow classification   Graphics Processing Unit (GPU)   GPU cluster   Mobile edge computing   Software Defined Networking   Software Defined Mobile Edge Computing (SDMEC)  

摘要： Mobile Edge Computing (MEC) provides different storage and computing capabilities within the access range of mobile devices. This moderates the burden of offloading compute/storage-intensive processes of the mobile devices to the centralized cloud data centers. As a result, the network latency is reduced and the quality of service provided for the mobile end users is improved. Different applications benefit from the large-scale deployments of MEC servers. However, the considerable complexity of managing large scale deployments of the sheer number of applications for the millions of mobile devices is a challenge. Recently, Software Defined Networking (SDN) is leveraged to resolve the problem by providing unified and programmable interfaces for managing network devices. Most of the current SDN packet processing services are tightly dependent on the packet classification service. This primary service classifies any incoming packet based on matching a set of specific fields of its header against a flow table. Acceleration of this basic process considerably increases the performance of the SDN-based MEC. In this paper, the hierarchical tree algorithm, which is a packet classification method, is parallelized using popular platforms on a cluster of Graphics Processing Units (GPUs), a cluster of Central Processing Units (CPUs), and a hybrid cluster. The best scenario for the parallel implementation of this algorithm on the CPU cluster is that which combines OpenMP and MPI. In this case, the throughput of the classifier is 4.2 million packets per second (MPPS). On the GPU cluster, two different scenarios have been used. In the first scenario, the global memory is used to store the rules and the Hierarchical-trie of the classifier while in the second scenario we break the filter set in a way that the resulting Hierarchical-trie of each subset could be stored in the shared memory of GPU. According to the results, although the first GPU cluster scenario achieves a throughput of

关键词： 双向拉伸聚酯薄膜   电晕处理   表面张力  

摘要： 为了提高薄膜表面张力,增强薄膜表面的再加工特性,须对薄膜表面进行电晕处理。介绍了双向拉伸聚酯(BOPET)的电晕处理的原理,探讨了聚酯薄膜加工的要求,论述了影响电晕效果的因素以及经时变化特性。

关键词： 平滩白钨矿床   加里东期成矿   流体包裹体   S同位素   沸腾作用   成矿机制  

摘要： 平滩白钨矿床位于南岭西段的苗儿山-越城岭岩体西部,为一新发现的形成于加里东期的矿床。对平滩钨矿床中的含钨石英脉进行了流体包裹体的研究,依据矿物共生组合以及石英脉的穿插关系将其成矿过程划分为两个阶段:石英−白钨矿阶段(Ⅰ)和石英−硫化物阶段(Ⅱ)。从第Ⅰ阶段到第Ⅱ阶段,均一温度从260~380℃明显降低到240~300℃,其盐度也呈明显下降趋势(平均盐度分别为11.26%NaCleqv和8.61%NaCleqv)。激光拉曼成分分析结果显示,第Ⅰ阶段的流体包裹体中含有CO2、CH4和N2等气相成分,明显区别于第Ⅱ阶段。第Ⅰ阶段中一定比例的含子晶流体包裹体以及各阶段石英脉中金属硫化物的δ34S组成为(−0.491×10^−3^+2.065×10^−3),平均为+0.496×10^−3,表明其成矿流体来自于岩浆水。引起钨矿质沉淀的主要原因为成矿流体的沸腾作用;平滩钨矿主要为源自于地壳重熔的岩浆经高度的分异演化后,富含钨矿质的岩浆热液经历了沸腾作用所形成。

关键词： Flexible biomass particles   Fluidized bed riser   Dynamic characteristics   3D particle model   Collision model  

摘要： The heterogeneous properties of biomass particles make their processing difficult in the fluidized beds. To handle biomass particles more easily, the fluidization process of the flexible biomass particles in a cold fluidized bed riser was investigated in the present study. The behavior of biomass particles subjected to the air flow was studied via the Euler-Lagrange method. Meanwhile, the particles were analyzed via a 3D particle model, and the collision was considered based on the impulse-momentum theorem, Routh-Poisson method and Coulumb's law of friction. The dynamic characteristics of the simulated particles, the particle distribution and the bending degree were first presented and validate the established model and the analysis with relevant experimental data. Then the fluidization processes of flexible biomass particles were analyzed under different air velocities and feeding rates. The obtained results indicated that particle distribution in the riser is uneven, and it has the bottom-dense and up-dilute characteristic in the axial direction and the central-dilute and near-wall-dense characteristic in the transverse direction. The flexible particles mainly present the bending patterns during the fluidization. The particle concentration presents regular variation under different conditions. The present method is valid to predict the dynamic behavior of flexible biomass particles, and paves a useful way to understand the treatment process of non-spherical particles.

关键词： 液体表面张力系数   光纤   拉力传感器   拉脱法  

摘要： 基于法布里-珀罗干涉型拉力传感器,利用拉脱法测量了液体表面张力系数.设计制备出的光纤拉力传感器结合单频激光器、光纤环形器、光电探测器可使输出电压和拉力成正比,其灵敏度约为64.5 mV/N.利用其测量室温下水的液体表面张力系数(0.076±0.001)N/m,相对偏差为4.1%.

关键词： 表面疏水性能   纹理设计   MPS法   表面张力  

摘要： 对于结构较复杂的容器内壁,若采用具有一定差异疏水性能的材料组合形成一定的纹理设计可对其表面疏水性能进行进一步强化。为研究不同的纹理对疏水性能的影响,本文采用移动粒子半隐式法(Moving Particle Semi-implicit,,.MPS),在三维尺度下,基于表面自由能表面张力和固-液表面张力模型,设计并模拟分析了不同条纹对平板上液滴动力学行为的影响,为进一步研究具有不同疏水性能材料的组合纹理对壁面脱附性能的影响提供依据。

关键词： Compressor cascade   Blade-end treatment   Flow loss   Topological analysis   Vortex dynamic mechanism  

摘要： Elucidating the underlying mechanism of the vortex dynamics in compressors is essential for determining the sources of the flow losses in compressor cascades. Hence, the effects of blade-end treatments on a linear compressor cascade should be analyzed at the microscale. In this study, the design parameters for various blade-end treatment methods were determined based on the topological structure of the saddle and spiral points on the blade surface. Then, based on the results, the underlying mechanism of the corresponding vortex dynamics was determined. The results showed that the total flow loss is primarily determined by the passage and concerted shedding vortices and the profile losses. The positive effect of the blade-end treatment is that it weakens the vortex structures, while its negative effect is that it causes the low-energy fluid clusters to converge into a separation bubble. However, the negative effects are compensated for by the positive, resulting in a significant reduction in the total flow loss. Furthermore, the changes induced in the pressure gradients by the treatments were also analyzed in this study. Thus, the microscale relationship between the vortex structure and the flow loss was clarified and the suitability of various blade-end treatment for preventing cascaded flow losses was analyzed in this study. (C) 2020 Elsevier Masson SAS. All rights reserved.

关键词： Rolling circulating fluidized bed (RCFB)   Rolling amplitude Theta   Rolling period T   Improved cluster renewal model (ICRM)   Heat transfer coefficient  

摘要： This paper presents a novel method to predict the gas layer thickness delta' in an improved cluster renewal model (ICRM) to calculate the heat transfer coefficient h', for a rolling circulating fluidized bed (RCFB). Eulerian-Eulerian two-fluid model (TFM) with kinetic theory of granular flow is used to perform a numerical simulation. After comparing the pressure gradient -Delta p/Delta z' and the simulated heat transfer coefficient between multiphase and the wall h(gs) with previously published experiment data, the correctness and reliability of the simulation are able to be verified. In conclusion, firstly, the variation of h(c)s calculated from delta' in the ICRM is almost the same with hgs in the case that the RCFB undergoes the rolling motion. In order to quantitatively evaluate the proposed novel method, an error percentage a between h', calculated from delta' and h(gs) is 2.043% which is less than 5%. This certified that the novel method to predict delta' in the ICRM has higher accuracy to calculate h', Secondly, h', calculated from delta' is mainly influenced by rolling amplitude 0 rather than by rolling period T. Specifically, with the increase of 0, amplitudes of Ts are decreased, which is caused by the increased heat transfer and the decreased (5' between cluster and wall. The decreased amplitudes of T-s are able to increase heat transfer efficiency, which eventually increases h'c, Thirdly, in the case that normalized rolling period tIT is changed from 0 to 0.5, higher h', calculated from delta' in Region I results from the large local cross-sectional particle volume fraction go, 1 in Region I with a smaller delta', while lower h', calculated from (5' in Region III results from the smaller clo,1 in Region III with a larger delta'. Therefore, it is concluded that h'(c), calculated from delta' is able to well predict the bed-to-wall heat transfer coefficient of the RCFB even if the rolling motion is considered. (C) 2020 The Society of Powder Technology Japan

关键词： coarse wood   fluidized bed   grindability   semi-biochar   thermogravimetric characteristics  

摘要： For the utilization of leftover materials from furniture factory, a two-step pyrolysis, an initial treatment at mild temperature followed by a fast pyrolysis step, in a fluidized bed reactor was proposed in this study. The grindability of semi-biochar samples after the mild temperature pyrolysis was studied. The fast pyrolysis characteristics and kinetics parameters of the semi-biochar samples were also investigated by thermogravimetric analysis. Results showed that an improvement in the grindability characteristics was observed. The grinding of semi-biochars that do not completely devolatilize mainly produces a mixture of fine particles and small fragments, whereas the semi-biochars that completely devolatilize have good grinding characteristic, and the main ground products are short and round particles. Most differential thermogravimetric (DTG) curves of the semi-biochar samples presented two peaks and four common stages. With increase of the temperature or residence time in mild temperature treatment process, the decomposition intensity of hemicellulose and cellulose in grinding residues decreased gradually, while the decomposition intensity of lignin changed little. Peak DTG value ranging from 4%/min to 6%/min can be adopted to estimate the optimal operation condition for mild temperature pyrolysis. Three-dimensional diffusion model can accurately describe the fast pyrolysis of semi-biochar.